How are we managing energy efficiency?

We're now saving almost 13 GWh of electricity each year. That's the equivalent of the power used by over 2,200 homes in a year.

Some of our projects include:

modifying and replacing conventional lighting with LED technology at several sites. This includes our wastewater treatment plants and laboratories. By changing the lights at some treatment plants, we've saved about $300,000 a year

using smarter mixing techniques at wastewater treatment plants

minimising power use by aerators at wastewater treatment plants

installing more efficient pumps

investing in energy efficient buildings. Both our Parramatta head office and Potts Hill buildings have a 5-star NABERS rating. They also have a 5-star Green Star rating from the Green Building Council of Australia.

In 2015-16, we generated the equivalent of 21% of our electricity needs from renewable sources - enough to power over 15,000 homes each year.

Here's how we do it.

Generating electricity from wastewater

Through a process known as cogeneration, we're turning waste methane gas (biogas) into electricity and heat. This helps power our wastewater treatment plants.

Biogas is a waste product naturally created during wastewater treatment where wastewater sludge is broken down by bacteria in anaerobic digesters.

We capture this biogas and convert it into electricity using a gas engine that simultaneously produces power for the treatment plant and heat. We re-use much of this waste heat to maintain the temperatures in our wastewater sludge digesters, keeping the reaction going to make more biogas.

We have 11 cogeneration units at 8 sites: Bondi, Warriewood, Malabar, North Head and Cronulla wastewater treatment plants, and at Glenfield, Liverpool and Wollongong water recycling plants.

This is one of our cogeneration plants that produces electricity from wastewater.

Producing water power (hydroelectricity)

We have three hydro-electric generation plants. This includes a hydro-electric generator at North Head Wastewater Treatment Plant.

Treated wastewater passes down a large drop shaft on its way to a deep ocean outfall. This energy is captured by a hydro-electric generator.

We also produce hydro-electricity from the water supply pipelines from Woronora Dam and from Warragamba Dam to Prospect Reservoir.

These hydro power plants use pressure reduction and gravity flow in water and wastewater streams to generate energy.

This is how we produce electricity using the power of water.

Using solar photovoltaic and solar hot water (solar power)

We've installed:

a 30 kW solar pvarray on our computer data centre

a 60 kW solar electric system on the roof of our Potts Hill office building to provide power to the offices

70 kW of solar power across a number of sites

solar hot water systems in many of our depots and treatment plants.

We're now planning another 300 kW of solar power. If approved, they'll be commissioned in the next two to three years.

Turning food waste into energy (co-digestion)

We're investigating how to use trucked food waste streams to increase the amount of energy generated at our wastewater treatment plants.

This innovation could:

reduce operating costs, helping us keep bills low

reduce carbon emissions caused by putting this waste into landfill

turn more waste into renewable energy - reducing both the waste stream and impacts on the environment.

The waste streams we're investigating include:

glycerol

commercial and household food waste

beverage and dairy waste

fats, oils and grease.

In October 2014, we started a 12 month glycerol trial at Bondi Wastewater Treatment Plant. This program proved that a wastewater treatment plant could receive trucked organic waste and convert it to energy for the plant. The program helped Bondi become our first wastewater treatment plant to generate more electricity than we need to run the entire wastewater treatment plant.

On the back of Bondi plant's success, we're introducing co-digestion into our Cronulla WWTP. It's expected that this plant will become operational in the middle of 2016. This plant will take pulped fruit and vegetable waste generated from commercial premises in the local Cronulla area. It's expected that this material will increase gas production and allow the plant to generate over 60% of its own electricity.

Looking forward

We see wastewater plants as potential clean energy generators of the future.

It's possible that some of our wastewater plants will generate more energy than they use in the future by:

increased pipe failures due to changes in soil structure and stability

large scale disruptions to electricity supplies.

We're well positioned to deal with future climate challenges and we'll continue to prepare and adapt where necessary.

Over the past 10 years, we've considered the impacts of future climate on water supply and demand planning. With other state agencies, we're addressing this risk by diversifying our water supply including:

dams

water recycling

water efficiency

desalination.

More recently, we've assessed the impacts of future climate on our:

infrastructure (worth about $39 billion)

operations

customers - so we have less service disruptions.

A key tool we use is AdaptWater. It calculates the:

consequences of climate change hazards

effectiveness of adaptation options to reduce risk.

National guidelines for climate change adaptation for water utilities

We co-led the development of the first national guidelines for climate change adaptation planning for Australian water utilities. The project was a Water Services Association of Australia (WSAA) initiative involving seventeen water utility partners who collaborated to produce these guidelines.

The document provides a decision framework that helps utilities understand and manage climate change risk within their business and start to integrate adaptation planning into their planning and decision making processes. Information is drawn from the extensive experience of the water industry to identify best practice and provide clear principles to guide the industry toward an organised, pragmatic and defensible approach to adaptation.